Method for supplying oxygen to combustion chambers



May 7, 1929.

A. o. HIGINBOTHAM 1,711,943

METOD FOR SUPPLYING OXYGEN TO COMBUSTION CHAMBERS Filed July ll 1925 v E 0 24 F. lg: 3. INVENTOR.

2a BY L? 1 \f'l!' @MM l ATTORNEY.

Patented Mey 7, 1929.

unirse STATES l 1,711,943- PATENT oFF'I(2a;v

.ARTHUR O. HIGNBOTI-IAM, OF DENVER, COLORADO, ASSIGNOR OF NEfHALF VLAM A. WEIGELE, OF DENVER, COLORADO: i.

To WIL;

METHOD'FOR SUEPLYING TO COMBUSTION QItlIAlVIIEIRS.y "j

'riginal applicationflcd August 15, 1924, Serial No. 732,323. Divided and this application filed 1 July 11, 1925. SerialNo. 43,043. i

This invention relates to anv improved method of admitting oxygen to the fire bed of a boilerl or furnaceafter firing, whereby to prevent the formation of excessive smoke by a substantially complete combustion of the gases emanated from the burning fuel, and it is an object of the invention to produce this result by the automatically controlled admission of oxygen to the fire chamber at a predetermined rate.

A further object of the invention is to effect the practically complete combustion of every heat producing element of the fuel by a gradual admission of oxygen to the fire bed during a predetermined period of time;

An apparatus capable of carrying the improved` method of oxidation into practice has been illustrated in the'accompanying draw# ings, said apparatus having beeninore fully disclosed in my application for patent No. 732,323, filed August 15, 192,4, of which the present application is a division. y

ln the drawings in the several views` of which like part-s have been similarly designated,

Figure 1' represents a front view of ka portion of a furnace wall and a door closing the fire-opening thereof, .in association with mechanism for admitting oxygen to the firechamber of the furnace bya time controlled movement of a damper on the door, automatically produced when the door is closed after each replenishment of the fire. ln this connection, it is to be understood that while my invention as illustrated in the drawings, is particularly adapted for operation by movement of the furnace doorits objects may alsoibe attained by medium of handactuated mechanism or through the instrumentality of a moving part of a furnace, other than the fire-door, as forV example, the reciprocating piston-ram Vof a mechanical push Stoker; j A` Figure 2 is an` enlarged vertical section along the line 2 2, Figure 1;

` Figure 3, a vertical-*section taken onthe line 343, Figure 1; and l Figure 1i, a. section in a vertical plane designated by the line if-4, in Figure 1.

L The element-s of theimechanism illustrated in the drawings,co-operatively assembled in association with the hinged fire-door 5 of a furnaceo, vare apair of dampers normally closing a rectangular opening in the door through whichgin practice, air is admitted to the lire in the combustion chamber of the boiler, a rotary cam S which operates the dampeii's', and a time-mechanismul of the escapement type operatively connectedwith the cani. n I i The dampers .in their closed position'overl lap one another to completely cover theairopening of thev door inside of an outwardly projecting iiange 10 and they are hungupon kthe iange for pivotal movement about horizontal axes by means of shafts 12.

The shafts are providedat one of their ends projecting enteriorly of the iange, with crank-arms 13 and 14` connectodpbya har ,15 for conjoint movement and the upper rcrank arm 13 carries upon an elongated vwrist-rod 16, an anti-friction wheel 17A Whicli'bea'rs upon the peripheral edge of the cam.

The cam-element in itssiinplest fornicoir sists of a disk havingy a pcripheraifly grooved edge of irregularforim but it is preferably composed of a number of steps of correspending outlines but progressively decreas'- i ,1

ing diameters to vary the extent to which the dampers may be opened by rotation of the cam-element.

The anti-frictionwheel 17r Ato this end i slidably mounted on the wrist rod 16 l,of the camKV so that it may be adjusted from one step ,of the camv `element j tov *anothery across 1 s n i `tne entire width thereof.

, The cam is fixed at an ,end of a shaft 18 supported for rotation 4in openings of the i rectangular flange 10 kvaround the door-open? ing and connected at its opposite extremity with the gear-train-of the time-mechanism, contained'in .a housing 19whichis secured upon the door at aside ofthe iiange' opposite to the cani-element. e j n 'i The time-mechanisni is operated' by a coiled spring 2O disposed between a shoulder 21 on an oscillating lever 22 operatively con- CII nected withthe drive wheel' of the mecht anism, and a thereto opposed;shoulder23 on a bell crank 211 which is inou'ntejdfto rjock in bearings at the lower portion of thejdofor. The lever 22 is loosely lmounted on the shaft of the drive wheel 34 and its operative I connection with lthe latter Iis:establishr-id by the medium of a pawl, hereinafter to be described. i

j A 1od`25 fastened on the levc'rand extending ico

loosely! through "can lopening of the shoulder on the bell crank, passes through the spring to prevent its lateral deflection.

A pin 26 on the arm of the bell crank opposite to that engaged by the spring, passes loosely through an opening in the door to engage the frame of the boiler around the fire-opening, when the door is in the closed position.

The connect-ion between the lever and the time-movement is established by means ofa pivoted pawl 27 which normally engages with a notched wheel Q8 at the end of the spindle of the drive wheel of the movement, upon which -the lever is supported.

Lugs 29 and 30 on the housing of the timemechanism limit the arcuate movement of the lever as will hereinafter be more fully explained-- i The time-mechanism is controlled by an adjustable escapement 31 of suitable construction. A simple and practical form of escapement, shown in the drawings, consists of a vertical oscillatory shaft 32 which carries at its upper end two simultaneously adjustable opposed weights 33. By varying the distance of these weights from the axis of oscillation of the shaft, the velocity of the time-mechanism may be accurately regulated.

Then the fire-door is in its normal closed position, its air-opening is tightly closed by the lapping dampers and the time-mechanism is in a condition of inactivity owing to the expanded condition of the spring. The anti-friction wheel on the crank-arm of the upper damper is placed in one of the grooved steps of the cam, according to the extent to which the dampers are to be opened during the predetermined time period, and the pawl on the lever is engaged in one of the notches of the wheel 28 on the shaft of the drive wheel on the time-mechanism.

In case it is desired to close the fire-door without actuation of the damper-operating time-mechanism, the pawl is disengaged from the wheel as shown in broken lines in Figure 2.

lVhen the lire-door is opened for the purpose of replenishing the lire in the combustion chamber of the furnace, the pin 26 on the bell crank lever 24 is projected through the opening of the door by gravity of the parts with which the lever is associated and the lever 22 is by the same influence moved to the position shown in Figure 2. The opening through which the pin passes is sufliciently large to permit of the slight lateral displacement of thepin caused by the arcuate movement of the end of the bell crank arm.

Vhen, after the fire has been coaled, the door is returned toits closed position, the pin by contact with the furnace wall, compels the bell crank to move about its axis and the corresponding movement of the shoulder 23 compresses the spring against the opposed shoulder of the lever 22 which is held through the medium of the pawl 27 by the frietional resistance of the timemechanism of which it is a part. rlhe upper arm of the bell crank entends at this point in` the operation, at an acute angle to a perpendicular passing through its pivotal axis, thereby compelling the spring to exert the force of its expansive movement upon the lever 22 and reducing the tendency of the spring to open the lire door by a reverse movement of the bell crank, to the minimum.

The expansion of the spring causes the time-mechanism to operate through engagement of the pawl 27 with the notched wheel 28 until the lever Q2 engages the stop 30 when its movement is automatically discontinued.

rlhe movement of the mechanism and the rate of consequent rotation of the cam shaft 18, are controlled by the adjustable escapement, `which thereby predetermines the time period during which the dampers are opened and closed and regulates the operation ac-` cording` to variable` circumstances, such as the kind of fuel supplied to the furnace or the quantity of fuel fed into the fire chamber of the furnace at one time,

The rotary motion of the shaft 18 is, through the medium of the cam, converted into a gradual opening movement ofthe dampers to an extent determined by the peripheral shape of the step of the cam with which the wheel on the crank-arm of the upper damper is in contact. Thus, when the cam rotates in the direction of the arrow C in Figure` 4, the dampers' are gradually opened by upward movement of the wheel 17 until the latter passes the point ofgreatest diameter of the cam when the wheel is lowered under the influence of its own weight and that of the other members of the movement with which it is associated,

until the dampers are again in the closed .j

position.

The duration of the damper movement is determined by the rate of operation of the time-mechanism under control of its escapement governor and by moving the contact wheel from one step of the cam to another, or by interchanging the `cam with another of different shape, the proportionate lengths of the gradual opening and closing movements of the dampers may be varied.

The extent to which the dampersV are opened during the time period predetermined as stated hereinabove is measured by the diameter of the cam, and thus may likewise be varied by adjustment of the contact wheel or by the use of different cams as hereinbefore explained.

The air entering the combustion chamber of the furnace past the gradually opening dampers, may be preheated and diffused by contact with suitably constructed bafie plates disposed in the opening of the door as indicated at 35 in Figure 3, and by proper regulation of the movement of the dampers as hereinbefore described, the air supply may be varied according to the requirements of the fuel, to form a substantially perfect combustible mixture with the gases arising from the burning fuel, and thereby prevent the formation f smoke.

, Having thus described my invention vvhat I claim and desire to secure by Letters Patent is:

1. The method of oxidizing gases evolved from fuel in a combustion chamber, consisting in automatically supplying air directly to the chamber in a gradually increasing quantity during a predetermined period of time.

2. The method of oxidizing gases evolved from fuel in a combustion chamber', consisting in automatically supplying air directly to the chamber in a gradually increasing and subsequently gradually decreasing quantity during a predetermined period of time.

The method of oxidizing gases evolved from fuel in a combustion chamber having a fire door, consisting in closing the fire vdoor after the fire has been replenished, supplying air directly to the replenished fire in the chamber in an increasing quantity to a predetermined peak, maintaining the supply 0f air at the peak for a predetermined period of time, and then decreasing the quantity to zero.

4. The method of oxidizing gases evolved from fuel in a combustion chamber, consist ing in automatically supplying air directly to the chamber in an increasing quantity, continuing the maximum supply of air during a predetermined period of time, and then decreasing the quantity.

5. The method of oxidizing gases evolved from fuel in a combustion chamber, consisting in the introduction of air directly into the chamber shortlyafter charging the same, in a gradually increasing quantity to a giv.n en peak and then decreasing said quantity to zero. i

In testimony whereof I have affixed my signature.

ARTHUR o. HIGINBOTHAM. 

